Variable displacement pump



Sept. 18, 1951 T. M. MouLDl-:N

VARIABLE DISPLACEMENT PUMP Filed March 5, 1948 \"`gqllllllulnlll By /1/5A Troy/sys Patented Sept. 18,` 1951 UNITED STATES PATENT oEFlcE VARIABLEDISPLACEMENT PUMP Tony M. Moulden, Montrose, Calif.

Application March 5, 1948, Serial No. 13,305

(Cl. B-42) 9 Claims.

My invention relates to the pump art, and particularly to a variabledelivery pump capable of delivering fluid at a constant discharge ratebut adapted to be adjusted to vary said discharge rate in accordancewith requirements.

One object of the invention is to provide a pump, of the class referredto, having rotary pumping means for pumping the fluid, a dischargemanifold, a by-pass manifold, and rotary valve means interposed betweenthe pumping means and the discharge manifold and between the pumpingmeans and said by-pass manifold, said valve means having an opening incontinuous fluid communication with said pumping means, said valve meansbeing adapted to be rotated to one position to establish fluidcommunication between said pumping means and the discharge manifold, toa second position to effect fluid communication between said pumpingmeans and said by-pass manifold, or to positions intermediate said firstand second positions to effect fluid communication between said pumpingmeans and both said discharge and by-pass manifolds. By this improvedvalve construction, the pumping means can be operated at a constantspeed to deliver a constant volume of fluid to the rotary adjustablevalve means which then serves to direct all or a portion of the fluidflow to 'the discharge manifold to maintain a conetant delivery rate ofthe iiuid from the pump A device, as established by the setting of thevalve means.

It is another object of the invention to provide a pump device of thetype indicated in which a plurality of said pumping means is arranged ina pump chamber and connected for unitary rotation, the pumping meansbeing adapted to draw iiuid from an intake manifold through a series ofindependent first ports and deliver the fluid to the rotary adjustablevalve means through a series of second ports, there being a first andsecond port for each pumping means.

In accordance With another object of my invention, the aforementionedrotary valve means has a plurality of the valve openings, these openingsbeing spaced axially of the valve means and arranged at differentcircumferential angles or, in other words, arranged at progressivelygreater angles from one end of the valve means toward the other endthereof. By this novel structure, the valve means can be rotated todifferent positions of angular adjustment to establish flow of the fluidinto either or both the discharge manifold or by-pass manifold so thatany portion of the combined delivery of the individual pumping means mayiiow to the discharge side of the pump device so that the delivery rateof the multiple pump means can be selectively varied from zero to amaximum value with an infinite number of intermediate delivery rates inaccordance with the requirements. The improved pump device thus hasparticular utility in the fluid circuit of a fluid motor or the like,the speed of operation of the motor being directly proportional to therate of delivery of the fluid to the motor by the pump device.

Another object is to provide a pump device, of the character referredto, embodying check valve means which function to maintain the fluid inthe discharge manifold constant regardless of the number of pumpingmeans delivering fluid to the discharge manifold, said check valve meansbeing adjustable from .the exterior of the pump device to set them for aselected fluid pressure. Preferably, the check valve means are arrangedin multiple, one for each pump means, and normally adapted to closepassages extending between the valve means and the discharge manifold,said check valve means being movable, against spring means, in responseto predetermined pressure diferentials between the pump chamber anddischarge manifold, to permit passage of the pumped fluid into thedischarge manifold and the pressure side of the line in which the pumpdevice is incorporated.

Another object of the invention is to provide an automatic control meanswhich is operative to maintain a predetermined substantially constantpressure in the discharge side of the pump device, said control meansacting, in response to slight variations in pressure in the dischargemanifold, to automatically rotate the valve means and adjust itsopenings with respect to the ports extending between the valve chamberand the discharge and by-pass manifolds so as to compensate for suchvariations and thus maintain the discharge pressure and delivery rate ofthe pump device substantially uniform.

A further object of the invention is to provide a pump device which isespecially simple in construction and economical to manufacture andservice, one which is positive in maintaining a pre-selected pressureand rate of delivery, and one which is capable of minute adjustment toproduce an infinite number of fluid delivery rates.

Further objects of my invention will be apparent from the followingdetailed description and from the drawing, which is intended for thepurpose of illustration only, and in which:

Fig. 1 is a front elevational view of my improved variable delivery pumpdevice;

Fig. 2 is a cross-sectional view through the pump device, taken on line2-2 of Fig. 1;

Fig. 3 is a sectional plan View, taken on line 3-3 of Fig. 1;

Fig. 4 is a cross-sectional view through the valve member, taken on line4-4 of Fig. 3; and

Fig. 5 is a view similar to Fig. 1, showing an automatic control meansfor rotating the valve means.

Referring to the drawing in detail, my improved pump device includes ahousing I9 which may be in the form of a rectangular block and suitablybored and machined at spaced intervals to provide an inlet manifold II,a pump chamber I2, a valve chamber I3, a discharge manifold `I4, and aby-pass manifold I5. The housing I0 is also bored transversely toprovide a series of first ports I6 communicating between the inletmanifold II and the pump chamber I2, and another series of second portsII aligned with the first ports and extending between the pump chamberI2 and the valve chamber I3. Extending between the valve chamber I3 andthe discharge manifold I4 is a series of inclined third ports IB, and aplurality of similar fourth ports I9 communicatesl between the valvechamber I3 and the by-pass manifold I5. The several ports I6, I'I, I 8,and I9 are arranged in transverse alignment, the present drawing showingeach series as comprising four of the ports. At the juncture between thethird ports I8 and the discharge manifold I4, these ports are providedwith valve seats 29. Aligned with the valve seats 29 are tapped holes 2|in the opposite side of the manifold I4, and screwed into each of theseholes is an adjusting plug 22 having an inner spindle 23 disposed in themanifold. Check valves 25 of the poppet type have tubular stems 26slidable on each of the spindles 23, and coil springs 2l surrounding thevalve stems between the heads of the valves, and the plugs 22 normallyfunction to yieldingly maintain the heads of the check valves seatedagainst the valve seats 20 as shown in Fig. 3.

Rotatable in the pump chamber I2 is a series of fluid pumping units 30of the well known gear type, each unit 30 being disposed in alignmentwith opposite first and second ports I6 and I1 and adapted to draw fluidfrom the inlet manifold II through a first port I6 and force the fluidthrough a second port II into the valve chamber I3. Each pumping unit3E) includes a pair of meshing gears 3l and 32, these gears beingrespectively keyed to shafts 33 and 34 and thus adapted for unitaryrotation. The shafts 33 and 34 are rotatable in bearings 35 and 36 (Fig.3) provided in end plates 3T and 38 which are suitably secured to thefront and rear surfaces of the housing I0. The shaft 33 projects fromthe end plate 38 and is adapted to be rotated at a substantiallyconstant speed by any suitable prime mover, such as an electric motor(not shown). The gear pump units 30 are held in axially spaced relationon their shafts by means of spacer elements or separators 39 which, ineffect, provide a series of four individual pumping chambers eachenclosing a pumping unit 39.

Rotatable in the valve chamber I3 is a valve member 40 which has areduced end 4I journalled in a bearing 42 in the rear end plate 31 andan axial extension or shaft 43 rotatable in a bearing 44 in the otherend plate 38, this shaft projecting from the last named plate to adaptit to be rotated either manually or automatically. As will be observedfrom the drawing, the rotary valve member 49 is provided with a seriesof four axially-spaced openings or transverse slots 45a, 45h, 45e, and45d, each slot extending throughout substantially 24:0o (Fig. 4). Theslots are staggered or advanced circumferentially, that is, successiveslots are disposed at increasingly greater angles with respect to theendmost slot 45a of the series, the angular difference between adjacentslots being herein shown as approximately 15. The slots 45a, 45D, 45C,and 45d are of equal size and each registers continuously with aseparate port II leading from the pump chamber I2.

In Fig. l the opposite ends of the individual slots are identified bythe same reference character, i. e., 45a, 45h, etc., and the valvemember 49 is illustrated as having been rotated to its extreme movementin clockwise direction. In this position of adjustment, each of theslots 15a-45d registers with an aligned pair of second and third portsII and I8 so that fluid can flow from the pump chamber I2, through allthe ports I1, through all the slots 45u-45d and enter the dischargemanifold I4 by way of the several ports I8. With the valve member 40adjusted to this position, all of the slots 45u-45d are out of registerwith the fourth ports I9 and thus no fluid will flow from the valvechamber I3 into the by-pass manifold and a maximum delivery rate of flowinto the discharge manifold I4 is established. On the other hand. if thevalve member 40 is rotated to a position wherein all the slots registerwith the ports I9 but are out of alignment with the ports I8, the entireflow of fluid is from the pump chamber I2 into the by-pass manifold I5so that the output of the pump de- Vice is reduced to Zero. When,however, the valve member 40 is adjusted to positions intermediate thetwo extremes of movement referred to above, certain of the slots 45u-45dregister with both the ports I8 and I9 so that the pump devicedischarges fluid into the manifold I 4 at a rate intermediate itsmaximum and minimum delivery rates. Consequently, by adjusting the valvemember 40 angularly in the valve chamber I3. infinite numbers ofintermediate delivery rates can be obtained to meet the requirements.

During the operation of the pump device, the check valves 25 function tocontrol the flow of fluid through the third ports into the dischargemanifold I4 so as to maintain the pressure and f discharge rate of thefluid substantially constant for any setting of the valve member 4I).Assuming that the valve member 4I) is adjusted to a position whereincertain of its slots, for example, 45a and 45h, permit at least partialflow of fluid through the ports I8 and I9, the pumping units 30 functionto deliver fluid to the discharge manifold I4, forcing the check valves25 to open position to permit such flow. At the same time, a portion ofthe pumped fluid may flow through the ports I9 and discharge into theby-pass manifold I5. This operation may continue as long as the fluidpressure in the discharge manifold I4 remains less than the fluidpressure in the port or ports I8. However, when such pressuredifferential is reduced to zero or, in other words, when the pressure inthe manifold I4 equals the pressure in the ports I8, the check-valves 25are moved against the seats 20 under the action of their springs 2l sothat further flow of fluid through the particular ports I 8 is checked.When this .condition prevails, the fluid is diverted through the portsI9 into the by-pass manifold. As the iiuidin the discharge .manifold isused to perform work in the system in which the `pump device isincorporated, the check valve -or check valves .again open to permitingress of fluid into the discharge manifold I4. Thus, during voperationof the pump device the check valves 25 open and close in response topressure differentials occurring between the ports I8 and the manifold`I4 and, as 'will be apparent, the Vcheck valves may assume a partiallyopen position to admit a limited flow of fluid into the manifold I4, theadjusted position of the valve member 40, that is, the number of slots5a-45d open to their respective ports i8 and I5, and the rate at whichthe discharged fluid is used to perform work lbeing important factorswhich control the function of the check valves.

As shown diagrammat-ically in Fig. l, the improved pump device may beincorporated in a fluid system which includes a reservoir B and a fluidmotor 5I. A hydraulic 1ine 52 leads from the reservoir to the inletmanifold II and another line 53 is connected between the vdischargemanifold I4 and the inlet `port of the fluid :motor 5I. A third line 54extends from the discharge port of the fiuid motor 5I to the reservoir5). By this system, fluid is drawn from the reservoir 5B and pumped intothe line 53, this pressurized fluid then being employed for operatingthe fluid motor 5I, the fluid then returning through the line 54 to thereservoir. A further line 55, connected between the `Ivy-pass manifold'i5 and the i 1ine V54, serves to by-pass fluid discharged into themanifold I5 to the reservoir. As previouslf.1 mentioned, the shaft 43can be rotated to adinet the valve member 40 angularly `in the valvechamber I3 so as to align or disalign any of the slots 15a-45d withtheir respective ports I8 and IQ and thereby control the delivery rateof the pump device. By so varying the rate of fluid delivery, differentrotational speeds of the uid motor can be readily obtained, so that thepump device, in additionto providing motive power for' actuatingthefluid motor 5I at various speeds, also serves as a governor tomaintain the speed of the motor substantially' constant. As will beapparent, when a load is imposed on the motor 5l, as is common when themotor must overcome inertia of a mechanism which it actuates, nuidpressure developed in the line 53 will maintain the check. valves closedto 'prevent further discharge of the pumped fluid into the manifold I4until the pressure within the discharge manifold is reduced to a valueless than the pressure within the valve chamber I 3, at which time thecheck valves open to establish now inte the line 53. The shaft 43 may beprovided witha handle to facilitate its rotation to different positionsof adjustment, and a pointer on the shaft may cooperate with a fixedarcuate dial or similar means to indicate the position of the valvemember, these parts not being herein shown as they may be of any typesuitable for the purpose.

My invention further contemplates the provision of an automatic controlmeans, shown in Fic. 5, which functions to maintain the selected fluiddelivery rate of the pump device constant. This control means consistsof a fluid cylinder 55 in which a piston 6I is slidable and which haspiston rod 62 slidable throu-gha head 63 screwed into an end of thecylinder. The rod E52 is operatively connected by meansof a link B4 toan arm 55 on the shaft 43 of the valve member 4D. A

spring 'I0 surrounding the rod B2 within the cylinder 60 has itsopposite ends bearing against the piston 6I and the head 63 respectivelyso that the spring normally tends to force the piston toward the rightso as to rotate the shaft 43 in clockwise direction and thus adjust thevalve member 40 to a position wherein all of the slots 45u-45d of thevalve member are in register with the ports I8 but out of register withthe ports I9 to produce a maximum rate of delivery of the fluid to thedischarge manifold I4. A 4fluid line 'Il is connected between thedischarge manifold I4 andthe right-hand end of the cylinder so that whenfluid pressure of a value which exceeds the force of the spring 'I0exists .in the manifold I4 and 1ine 1I, the piston 6I is forced towardthe left to rotate the shaft 43 and valve member 40 in counterclockwisedirection. Rotation of the valve member 40 in this directionprogressively closesl the individual ports I8 and opens the ports I9 soas to reduce the rate of delivery of uid into the discharge manifold I4.It will be noted that in the embodiment illustrated in Fig. 5, the checkvalves 25 are dispensed with, the control means 50, 6I, etc., beingemployed in lieu thereof. Since the pressure of the discharged fluid inthe manifold is proportional to the rate of fluid delivery, it followsthat by automatically adjusting the setting of the valve member fifi inresponse to variations in this fluid pressure, a substantially constantrate of fluid delivery is maintained. As will be apparent, the controldevice can be readily adjusted to operate at selected pressures in themanifold I4 by merely screwing the head 63 inwardly and outwardly in theend of the cylinder ED to vary the strength of the spring lll.

My improved fluid pump has been referred to herein as one of thevariable delivery type. The term variable delivery is appropriately usedonly insofar as the pump is capable of delivering fluid at variousselected but constant rates. In other Words, the present pump isintended for use in maintaining a constant preselected rate of flow. Bymy improved construction, the pumping elements are operated continuouslyat a constant speed to continuously deliver a yconstant volume of thenuid per unit of time the ultimate rate of fluid delivered to the systemin which the device is located being automatically controlled inresponse to variations in pressure in the discharge manifold. It istherefore unnecessary to increase or decrease the operational speed ofthe pumping elements and the pump device is thus greatly simplified.

While I have herein shown and described the improved variable deliverypump as embodied in two preferred forms of construction and as appliedto use in a particular manner, it will be obvious that modificationsmight be made therein without departing from the spirit of theinvention. Consequently I do not wish to be limited in this respect butdesire to be affordedV the full scope of the appended claims.

I claim as my invention:

1. A variable delivery pump, comprising: a housing having walls defininga fluid inlet manifold, a pump chamber, a valve chamber, a fluidpressure discharge manifold and a by-pass manifold, said housing alsohaving a plurality of first ports in fluid communication between saidinlet manifold and said pump chamber, a plurality of second ports innuid communication between said pump chamber and said valve chamber, aplurality of third ports in fluid communication between said valvechamber and said pressure manifold and a plurality of fourth ports influid communication between said valve chamber and said by-passmanifold, said first, second, third and fourth ports being equal innumber; a plurality of pumping means, each in alignment with one of saidfirst and second ports, disposed in said pump chamber and adapted forcontinuous, unitary operation; valve means movable in said valve chamberand provided with a series of axially spaced, transverse openings, eachopening being arranged in continuous alignment with one of said secondports and being disposed at progressively greater angles with respect toan endmost opening of said series, each of said openings being adaptedto also register with a said third and fourth port, said valve meansbeing adapted to be moved in one direction to successively align certainof its openings with said third ports and successively disalign other ofits openings with respect to said fourth ports so as to increase thevolumetric flow of fluid from said second ports into said third ports toincrease the delivery of fluid to said pressure discharge manifold, saidvalve means being also adapted to be moved in the opposite direction tosuccessively disalign certain of its openings with respect to said thirdports and successively align its other openings with said fourth portsso as to increase the delivery of fluid to said pressure dischargemanifold and increase the delivery of fluid to said by-pass manifold;and control means for moving said valve means.

2. A variable delivery pump, comprising: a housing having walls defininga fluid inlet manifold, a pump chamber, a valve chamber, a fluidpressure discharge manifold and a by-pass manifold, said housing alsohaving a plurality of first ports in fluid communication between saidinlet manifold and said pump chamber, apluralty of second ports in fluidcommunication between said pump chamber and said valve chamber, aplurality of third ports in fluid communication between said valvechamber and said pressure manifold and a plurality of fourth ports influid communication between said valve chamber and said by-passmanifold, said first, second, third and fourth ports being equal innumber; a plurality of pumping means, each in alignment with one of saidfirst and second ports, disposed in said pump chamber and adapted forcontinuous, unitary rotation; valve means rotatable in said valvechamber and provided with a series of axially spaced transverseopenings, each opening being arranged in continuous alignment with oneof said second ports and being disposed at progressively greater angleswith respect to an endmost opening of said series, each of said openingsbeing adapted to also register with a said third and fourth port, saidvalve means being adapted to be rotated in one direction to successivelyalign certain of its openings with said third ports and successivelydisalign other of its openings with respect to said fourth ports so asto increase the volumetric flow of fluid from said second ports intosaid third ports to increase the delivery of fluid to said pressuredischarge manifold, said valve means being also adapted to be rotated inthe opposite direction to successively disalign certain of its openingswith respect to said third ports and successively align its otheropenings with said fourth ports so as to increase the delivery of fluidto said pressure discharge manifold and increase the delivery of fluidto said by-pass manifold; and control means for rotating said valvemeans.

3. A variable delivery pump, comprising: a housing having walls defininga fluid inlet manifold, a pump chamber, a valve chamber, a fluidpressure discharge manifold and a by-pass manifold, said housing alsohaving a plurality of flrst ports in fluid communication between saidinlet manifold and said pump chamber, a plurality of second ports influid communication between said pump chamber and said valve chamber, aplurality of third ports in fluid communication between said valvechamber and said pressure manifold and a plurality of fourth ports influid communication between said valve chamber and said by-passmanifold, said first, second, third and fourth ports being equal innumber; a plurality of pumping means, each in alignment with one of saidfirst and second ports, disposed in said pump chamber and adapted forcontinuous, unitary operation; valve means movable in said valve chamberand provided with a series of axially spaced openings, each openingbeing arranged in continuous alignment with one of said second ports andbeing disposed at progressively greater angles with respect to anendmost opening of said series, each of said openings being adapted toalso register with a said third and fourth port, said valve means beingadapted to be moved in one direction to successively align certain ofits openings with said third ports and successively disalign other ofits openings with respect to said fourth ports so as to increase thevolumetric flow of fluid from said second ports into said third ports toincrease the delivery of fluid to said pressure discharge manifold, saidvalve means being also adapted to'be moved in the opposite direction tosuccessively disalign certain of its openings with respect to said thirdports and successively align its other openings with said fourth portsso as to increase the delivery of fluid to said pressure dischargemanifold and increase the delivery of fluid to said bypass manifold; aplurality of check valves in said pressure discharge manifold, eachoperative to permit fluid flow from a said third port into said pressuredischarge manifold when the pressure of the fluid in that port equals apredetermined value but adapted to close in response to a pressure dropof the fluid in said third port below said predetermined value so as tomaintain the fluid in said pressure discharge manifold at asubstantially constant pressure; and' control means for moving saidvalve means.

4. A variable delivery pump as defined in claim 3 and including: springmeans for actuating said check valves; and means for adjusting thetension of each of said spring means.

5. A variable delivery pump as dened in claim 3, in which each of saidthird ports is provided with a valve seat, each of said check valvesbeing engageable with one of said seats, and including: a spring meansnormally operative to seat each of said check valves; and adjustingmeans accessible from the exterior of said housing for adjusting thetension of each spring means.

6. A lvariable delivery pump, comprising: a housing having wallsdefining a fluid inlet manifold, a pump chamber, a valve chamber, afluid pressure discharge manifold and a by-pass manifold, said housingalso having a plurality of flrst ports in fluid communication betweensaid inlet manifold and said pump chamber, a plurality of second portsin fluid communication between 9 said pump chamber and said valvechamber, a plurality of third ports in fluid communication between saidvalve chamber and said pressure manifold and a plurality of fourth portsin fluid communication between said valve chamber and said by-passmanifold, said rst, second, third and fourth ports being equal innumber; a plurality of pumping means, each in alignment with one of saidrst andsecond ports, disposed in said pump chamber and adapted forcontinuous, unitary rotation; Valve means rotatable in said valvechamber and provided with a series of axially spaced transverseopenings, each opening being arranged in continuous alignment with oneof said second ports and being disposed at progressively greater angleswith respect to an endmost opening of said series, each of said openingsbeing adapted to also register with a said third and fourth port, saidvalve mea-ns being adapted to be rotated in one direction tosuccessively align certain of its openings with said third ports andsuccessively disalign other of it.t openings with respect to said fourthports so as to increase the volumetric flow of fluid from said secondports into said third ports to increase the delivery of fluid to saidpressure discharge manifold, said valve means being also adapted to berotated in the opposite direction to successively disalign certain ofits openings With respect to said third ports and successively align itsother openings with said fourth ports so as to increase the delivery ofiiuid to said pressure discharge manifold and increase the delivery offluid to said by-pass manifold; and means responsive to iluid pressurein said pressure discharge manifold for controlling the flow of fluidthrough said third ports into said pressure discharge manifold.

7. A variable delivery pump, comprising: a housing having walls defininga fluid inlet manifold, a pump chamber, a valve chamber, a iiuidpressure discharge manifold and a by-pass manifold, said housing alsohaving a plurality of rst ports in fluid communication-between saidinlet manifold and said pump chamber, a plurality of second ports influid communication between said pump chamber and said valve chamber, aplurality of third ports in fluid communication between said valvechamber and said pressure manifold and a plurality of fourth ports influid communication between said valve chamber and said by-passmanifold, said first, second, third and fourth ports being equal innumber; a plurality of pumping means, each in alignment with one of saidfirst and second ports, disposed in said pump chamber and adapted forcontinuous. unitary rotation; valve means rotatable in said valvechamber and provided with a series of axially spaced transverseopenings, each opening being arranged in continuous alignment with oneof said second ports and being disposed at progressively greater angleswith respect to an endmost opening of said series, each of said openingsbeing adapted to also register with a said third and fourth port, saidvalve means being adapted to be rotated in one direction to successivelyalign certain of its openings with said third ports and successivelydisalign other of its openings with respect to said fourth ports so asto increase the volumetric flow of fluid from said second ports intosaid third ports to increase the delivery of fluid to said pressuredischarge manifold, said valve means being also adapted to be rotated inthe opposite direction to successvely disalign certain of its openingswith respect to said third ports and successively align its otheropenings with said fourth portsrso as to increase the delivery of fluidto said pressure discharge manifold and increase the delivery-of iiuidto said by-pass manifold; and meansresponsive to iiuid pressure in saidpressure discharge manifold for controlling the total now of fluidthrough any or all of said third ports into said pressure dischargemanifold.

8. A variable delivery pump, comprising: a housing having walls defininga fluid inlet manifold, a pump chamber, a valve chamber, a fluidpressure discharge manifold and a by-pass manifold, said housing alsohaving a plurality cf first ports in fluid communication between saidinlet manifold and said pump chamber, a plurality of second ports influid communication between said pump chamber and said valve chamber, aplurality of third ports in fluid communication be'- tween said valvechamber and said pressure manifold and a plurality of fourth ports influid conimunication between said valve chamber and saidby-passmanifold, said rst, second, third and fourth ports being equal innumber; a plurality of pumping means, each in alignment with one of saidfirst and second ports, disposed in said pump chamber and adapted forcontinuous, unitary rotation; valve means rotatable in said valvechamber and provided with a series of axially spaced transverseopenings, each opening being arranged in continuous alignment with oneof said second ports and 'being disposed at progressively greater'angleswith respect to an endmost opening of said series, each of said openingsbeing adapted to also register with a said third and fourth port, saidvalve means being adapted to be rotated in one direction to successivelyalign certain of its openings with said third ports and successivelydisalign other of its openings with respect to said fourth ports so asto increase the volumetric flow of fluid from said second ports intosaid third ports to increase the delivery of fluid to said pressuredischarge manifold, said valve means being also adapted to be rotated inthe opposite direction to successively disalign certain of its lopeningswith respect to said third ports and successively align its otheropenings with said fourth ports so as to increase the delivery of fluidto said pressure discharge manifold and increase the delivery of fluidto said by-pass manifold; and automatic control means for rotating saidvalve means.

9. A variable delivery pump, comprising: a housing having walls defininga fluid inlet manifold, a pump chamber, a valve chamber, a fluidpressure discharge manifold and a by-pass manifold, said housing alsohaving a plurality of first ports in fluid communication between saidinlet manifold and said pump chamber, a plurality of second ports influid communication between said pump chamber and said valve chamber, aplurality of third ports in fluid communication between said valvechamber and said pressure. manifold and a plurality of fourth ports influid communication between said valve chamber and said by-passmanifold, said rst, second, third and fourth ports being equal innumber; a plurality of pumping means, each in alignment with one of saidfirst and second ports, disposed in said pump chamber and adapted forcontinuous, unitary rotation; valve means rotatable in said valvechamber and provided with a series of axially spaced transverseopenings, each opening beingarranged in continuous alignment with one ofsaid second ports and being disposed at progressively greater angleswith respect to an endmost opening of said series, each of said openingsbeing adapted to also register with a said third and foiirth port, saidvalve means being adapted to be rotated in one direction to successivelyalign certain of its openings with said third ports and successively.disalign other of its openings with respect to said fourth ports so asto increase the volumetric flow of uid from said second ports into saidthird ports to increase the delivery of uid to said pressure dischargemanifold, said valve means being also adapted to be rotated in theopposite direction to successively disalign certain of its openings withrespect to said third ports and successively align its other openingswith said fourth ports so as to increase the delivery of uid to saidpressure discharge manifold and increase the delivery of uid to saidby-pass manifold; and automatic control means responsive to variationsin pressure in said prssure discharge manifold for rotating said valvemeans; y l

TONY M. MOULDENi REFERENCES CITED The following references are of recordin the i'lle of this patent:

